Within the next few days I'll be 'brewing' 100 litres of ale from slightly concentrated sterile wort. I've used these kits before with decent results, but this time I want to try a liquid yeast instead of the packaged dry (Cooper's) yeast that's included in the box. So I bought a Wyeast 'Direct Pitch' smack pack (British Ale II) that allegedly contains 100 billion cells.

Not enough for this much wort, obviously, so I propose to boil up half a pound of dry malt extract to make a 1/2 gallon starter. When that's rolling nicely I'll use it to pitch this next mega-batch. Good idea? Bad idea? Any reason that wouldn't be satisfactory?

Much of my homebrewing knowledge, if you can call it that, dates back to Neolithic (i.e. pre-Internet) times, so until I can lay my hands on some good recent books on the subject, I thought I'd ask the question here.

What a handy tool! I don't even know what a stir plate is, but I will soon. Much obliged.
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GlasseyedMay 5 '14 at 18:41

Back with an instant update. Found this link, in case anyone's interested: byo.com/stories/projects-and-equipment/item/… Now that I'm getting back into home brewing, I'll probably build one myself, since it turns out I have all the necessary components. In the meantime I'll adjust my starter recipe to suit my present equipment.
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GlasseyedMay 5 '14 at 18:49

Nice. There's a significant difference in yeast starter growth between a stir plate and other methods; the brewers friend calculator has some references, especially to Kai's measurements. Yeast health and fermentation temp control are probably the two biggest improvements most homebrewers can make. Cheers!
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jsled♦May 5 '14 at 19:38

I'd be seriously underpitching, so I'll take your advice. As for books being pre-Internet--got a mild chuckle out of that--my modest home brewing collection dates back to the 70s and early 80s, when the general level of (accessible) knowledge was pretty abysmal compared to now.
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GlasseyedMay 6 '14 at 13:10